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An unstructured Monte Carlo ray-tracing method for solving radiative heat transfer in 3D gray semitransparent medium
摘要： Monte Carlo ray-tracing method (MCRTM) is widely used for solving the Radiative Transfer equation (RTE) due to its high accuracy and flexibility. In this paper, a MCRTM is developed for solving the radiative heat transfer in gray semitransparent media with complex geometries which are discretized by 3D unstructured grids. A novel algorithm associated to unstructured four-node tetrahedron element is proposed for generating random emitting positions of rays, and the ray tracing process is performed based on Beer's law. Meanwhile, radiation distribution factors are used for calculating radiative source terms which are loaded to the grid. The present method is first validated by comparing the predictive results with those from previous studies on a cubic enclosure, a 3D L-shaped enclosure, and a 3D elliptical enclosure, respectively. Furthermore, a radiation-conduction heat transfer problem is examined in a cylindrical enclosure. All the comparisons show that the present method is in good agreement with these previous cases. This method can be well adapted to various complex geometries. In addition, since the source term is calculated by the radiation distribution factor, which can be reused for different conditions as long as the volumetric radiative properties remain unchanged, this will bring great advantage when coupled with other heat transfer models such as conduction, convection, combustion, etc.
关键词： Monte Carlo ray-tracing method,Radiative heat transfer,Semitransparent medium,Radiation distribution factor,Unstructured grids
更新于2025-09-23 15:23:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Error Analysis of the Impulse Response on VCSEL-based Optical Wireless Communication Channel Using a Monte Carlo Ray-Tracing Algorithm
摘要： This article proposed a Monte Carlo ray-tracing method (MCRM) based on Gaussian beam emitter for optical wireless communication (OWC) channel estimation and established two typical indoor communication systems as uplink and full-link models. Formulas are given with targeted parameters for these two specific link models. The calculation results show that the impulse response of uplink models have twice larger and 10 ns faster than that of full-link models. Compared with the conventional Lambertian OWC systems, the Gaussian systems have larger impulse response and lower relative error, which indicates that Gaussian emitter is a promising candidate for indoor OWC system.
关键词： Channel estimation,VCSEL,Monte Carlo Ray-tracing method,Optical wireless communication
更新于2025-09-16 10:30:52
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DESIGN OF NONUNIFORM METALLIC ANECHOIC CHAMBER FOR RADIATION PATTERN MEASUREMENT
摘要： Antenna pattern measurement is an essential step in antenna quali?cation which should be done in anechoic chambers. The common method for construction of the anechoic chamber is to cover all inside walls by the electromagnetic absorbers. In this paper, a new method is presented to design a fully metallic chamber by controlling the electromagnetic wave propagation inside the chamber and guiding them to a piece of absorber. Therefore, a desirable quiet zone is formed inside the chamber while a great reduction of absorber usage is achieved. The proposed chamber is analyzed using ray tracing method, and its performance is evaluated by simulation which shows the practicality of the proposed chamber.
关键词： anechoic chamber,ray tracing method,antenna pattern measurement,electromagnetic absorbers,quiet zone
更新于2025-09-09 09:28:46
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Optical performance analysis of an innovative linear focus secondary trough solar concentrating system
摘要： The parabolic trough solar concentrating system has been well developed and widely used in commercial solar thermal power plants. However, the conventional system has its drawbacks when connecting receiver tube parts and enhancing the concentration ratio. To overcome those inherent disadvantages, in this paper, an innovative concept of linear focus secondary trough concentrating system was proposed, which consists of a fixed parabolic trough concentrator, one or more heliostats, and a fixed tube receiver. The proposed system not only avoids the end loss and connection problem on the receiver during the tracking process but also opens up the possibility to increase the concentration ratio by enlarging aperture. The design scheme of the proposed system was elaborated in detail in this paper. Besides, the optical performance of the semi and the whole secondary solar trough concentrator was evaluated by using the ray tracing method. This innovative solar concentrating system shows a high application value as a solar energy experimental device.
关键词： secondary parabolic trough solar concentrator,optical performance,concentration ratio,linear focus,ray tracing method
更新于2025-09-09 09:28:46